Dust control in potash products



United States Patent Ofiiice 3,063,800 Patented Nov. 13, 1952 3,063,800DUST CONTROL IN POTASH PRODUCTS William B. Daney, Carlsbad, N. Mex.,assignor to inteb national Minerals & Chemical Corporation, a corpora-The present invention relates to a method for the con More particularly,

trol of dusting in potash products. the present invention relates to theapplication of oil to finely divided potash products to substantiallyprevent dusting.

The problem of controlling dust created by the handling of finelydivided potash materials has been a universal problem. When loading orunloading such materials in large quantities, the dust thus createdcauses poor working conditions, loss of a large portion of the productand possible contamination of surrounding areas. For example, whenloading a freight car with finely divided potash material, it isfrequently necessary for the operator of the loading apparatus to wear adust mask for protection. Sometimes the dust becomes so dense duringloading and unloading operations, it is necessary to temporarily ceaseoperation until the dust has settled. This results not only in a loss oftime but also an increase in operating costs.

The problem of controlling the dusting of potash material is complicatedby the light color of the material and by the necessity of futureprocessing of the material. It will be apparent that means to preventdusting of potash material desirably will not substantially adverselyaffect the color of the material and will not change the characteristicsof the material to substantially affect subsequent processing.

It is a primary object of this invention to control the dusting offinely divided potash material.

It is a further object of this invention to control the dusting offinely divided potash material without substantially adversely afiectingthe color of the material.

It is yet a further object of this invention to control the dusting offinely divided potash material without substantially adversely affectingthe quality of the material.

An additional object of the present invention is to reduce loss of afinely divided potash material through dusting.

Another object is to improve the handling conditions of a finely dividedpotash material.

Still another object is to provide more eflicient operating conditionswhen handling a finely divided potash material which creates a largeamount of dust.

According to the present invention, finely divided potash material iscontacted with a small amount of viscous mineral oil which conforms tocritical specifications. The

potash material treated in accordance with this invention may besubjected to normal handling incident to loading Band unloadingoperations and the like and will not exhibit any pronounced tendency todust. The color integrity of the material is maintained and the qualityof the material is preserved.

As employed herein, potash materials embrace potassium chloride,potassium sulfate and similar salts of potassium. The term potash hasattained a recognized meaning in the art.

The mineral oils which are employed in the practice of the presentinvention are characterized by a pour point of from about 30 F. to about120 F., a viscosity from about 50 SSU to about 350 SSU at 100 F., adistillation temperature above about 500 F., a distillation end pointbelow about 1000 F., a distillation residue of not more than about 15%,and an aromatic content of not more than about 60%.

Preferred mineral oils which are employed in the practice of thisinvention are characterized by a pour point of from about 35 F. to about100 F., a viscosity from about 100 SSU to about 310 SSU at 100 F., a 10%distillation temperature from about 500 F. to about 700 F., adistillation end point below about 900 F., a distillation residue of notmore than about 15%, and an aromatic content of not more than about 50%.

From the foregoing specifications it will be apparent that an asphaltbase oil conventionally employed for dust control on highways isinapplicable, inter alia, be cause of adverse effects to the color ofpotash products. Crude oils of various types are too wide in boilingrange and often too high in asphaltic content for optimum dust controlperformance. Gasoline and kerosene fractions, as well as diesel oilfractions, have too low a viscosity to prevent dusting. Only those oilswhich conform to the above specifications have been found suitable forthis invention.

Suitable oil fractions for use in the present invention can be obtainedfrom lubricating oil stocks in paraffin on wax distillates which resultfrom the distillation of crude petroleum oils and the rcdistillation ofcracked petroleum,

stocks and heavy petroleum distillates. These materials provide thedesired results of the present invention pro refining crude petroleumoil from Eddy and Lea Coun-' ties, New Mexico. This fractionator stillbottoms is available from the Malco Refinery, Artesia, New Mexico.

In obtaining such a material, crude oil is first distilled at reducedpressure until an overhead vapor temperature of about 700 F. isobtained. The overhead fraction obtained by vacuum distillation at about700 F. is termed vacuum gas oil. This stock oil is fed to a catalyticcracking unit from which fractionator bottoms, a

preferred petroleum fraction for dust control, is obtained.

Table I below identifies five representative oils which conform to thespecifications set forth above and which provide excellent dust controlfor potash materials. Oil A represents the fractionator still bottomsdiscussed above. It will be apparent that the oils embraced by thisinvention contain a substantial paraflinic hydrocarbon content.

TABLE I Oil A B G D E Distillation range:

Initial boiling pt., F 265 585 648 580 600 End point, F 875 975 1, 0001, 000 1, 000 Distillation recovery, percent 85 97. 5 85 85 85Viscosity:

F., SSU 310 300 150 61 290 F, SSU--- 153 148 78 46 132 210 F, SSU 51 4034 49 Pour point, F 80-90 90-100 Retroactive index 1. 543 1. 520 1.530 1. 470 1. 512 API gravity 18.5 21.2 17.8 35.5 22.5 Specific gravity60/60 F .9433 9267 9478 8473 9188 Ash, percent 0 0 Molecular weight 302355 255 275 322 Gonradson 0, percent 2-4 0.3 Sulfur, percent 1. 93 0.80 1. 34 0 2. 20 Paraffin and naphthene 50. 3 56.0 40 86 52 Aromatic 49.5 44. 0 60 14 48' Unsulfonatable material..- 60 70 It will be apparentthat blends of oils may be employed in the present invention providedthat the characteristics of the blend conform to the specifications ofthis invention. For example, a blend of a light lubricating oil stockand a crude oil fractionator bottom in a volumetric ratio ofabout 1 toabout 4 may be employed to provide a desirable dust control. In such ablend it is advantageous to employ a distillate fraction in conjunctionwith a fractionator bottom fraction. In this manner it is possible tomaintain a maximum viscosity yet maintain a minimum proportion of colorforming bodies in the mineral oil. The precise choice of stocks and theproportions in which they are employed is readily within the skill ofthe art.

In the event that the mineral oil exhibits an undesirable odor, a smallamount of another oil such as pine oil can be admixed with the mineraloil. Proportions of about 1 gallon of pine oil per 1,000 gallons ofmineral oil effectively overcomes any undesirable odor of the mineraloil without adversely afiecting either the quality or color of thepotash material.

The mineral oil is applied in amounts from about 0.25 to about 5 gallonsper ton of potash material to be treated. Somewhat higher proportionsmay be employed but adverse effects to the color and quality of theproduct may result. Conversely, a somewhat lower proportion may reducedusting but will not substantially prevent dusting. The mineral oilpreferably is employed in amounts from about 0.5 to about 1.5 gallonsper ton of potash material.

Mixing of mineral oil with the potash materials may be accomplished inany manner which will provide a substantially even distribution of theoil throughout the potash materials. Commercial spray apparatusincluding paint spray apparatus advantageously can be employed. A thinlayer of potash on a moving belt can be contacted with an oil spray toachieve the oil coating of this invention. It will be apparent thatother means also can be employed to provide the coated product of thisinvention. No subsequent heat treatment or the like is required ordesirable.

In one desirable method of admixing materials, potassium sulfate whichis to be loaded for shipping in large quantities is admixed with amineral oil as hereinabove described by spraying the potash with themineral oil at the discharge end of a conventional pan heater used instandard loading operations. The oil-treated potassium sulfate on theway to a receiving car subsequently is passed through a screw conveyorwherein additional mixing is accomplished.

The following specific embodiments are included for purposes ofexemplification only and in no way are intended to limit the scope ofthis invention.

Example I I Forty tons of potassium sulfate were sprayed with 47 gallonsof the above described oil A. The sprays were located on the dischargeend of a pan feeder in a loading operation. The oil-treated material wassubsequently passed through a screw conveyor in such a manner that themixing of the potassium sulfate and the fractionator bottoms wascompleted.

The treated material, as well as an equal quantity of untreatedpotassium sulfate, was loaded and shipped to a distant point. Thetreated material created essentially no dust in both the loading andsubsequent unloading operations, Whereas the untreated material dustedto such an extent that about 6% of the product was lost.

Representative samples amounting to 300 pounds of the treated potassiumsulfate and 300 pounds of untreated potassium sulfate were subjected toa screen analysis, the results of which appear in Table 11 below.

TABLE Regular Oiled KzSO; K2304 i6 mesh 3 i 8-..- 5 -|l0 l0 7 +14 12 9+20 17 13 +28 25 21 +35 38 34 +48. 47 44 +05 59 57 +100 75 72 --l00 2528 Example 11 TABLE III Percent increase in calrlng tendency of treatedpotassium sulfate Ratio 1 K20:

Although these figures show a negligible increase in caking tendenciesof the treated product, the lumps formed were approximately half as hardas those formed by the untreated sulfate material. Accordingly, theslight increase in caking of potassium sulfate-superphosphate mixturewas not significant.

Example III Granulation tests were carried out by formulating thepotassium sulfate treated with oil A into a 5-10-15 (N, P, K)fertilizer. The formula for this grade was as follows:

81 lbs. 60/60 B. H 271 lbs. 37% nitrogen UAL-C solution 1,025 lbs. 19.5%superphosphate I 590 lbs. sulfate of potash 193 lbs. dolamite fillerWater The granulating test consisted of granulating the above formulausing various amounts of Water to effect different degrees ofgranulation. The use of sufiicient water or liquid medium providedacceptable granulation.

The mineral oil treatment of the potassium sulfate did not change theinstantaneous solubility nor the wetability of the material to anymeasurable degree. Instantaneous solubility was found to be exactly thesame for both the untreated and treated materials. The oil treatmentalso did not change the analysis, as both the treated and untreatedpotassium sulfate showed an analysis of 50.32% K 50 Since obviousmodifications of this invention will be apparent to those skilled in theart, it is intended that this invention be limited only by the scope ofthe appended claims.

I claim:

1. The method of controlling dusting of finely-divided potash whichconsists essentially of intimately admixing finely-divided potash withfrom about 0.25 to about 5 gallons of mineral oil per ton of potash tosubstantially coat said potash with said mineral oil, said mineral oilbeing characterized by a pour point of from about 30 F. to about 120'F., a viscosity of from about 50 SS to about 350 SSU at 100 F., adistillation temperature above about 500 F., a distillation end pointbelow about 1000 F a distillation residue of not more than about and anaromatic content of not more than about 60%.

2. The method of claim 1 in which the mineral oil is employed in amountsfrom about 0.5 to about 1.5 gallons per ton of potash.

3. The method of claim 1 wherein the mineral oil is a petroleum oil.

4. The method of controlling dusting of finely-divided potash whichconsists essentially of intimately admixing finely-divided potashWithfrom about "0.25 to about 5 gallons of mineral oil per ton of potashto substantially coat said potash with said mineral oil, said mineraloil being characterized by a pour point of from about 35 F. to about 100F., a viscosity of from about 100 SSU to about 310 SSU at 100 F, a 10%distillation temperature from about 500 F., to about 700 F., adistillation end point below about 900 F, a distillation residue of notmore than about 15% and an aromatic content of not more than about 50%.

5. The method of claim 4 wherein the mineral oil is employed in amountsfrom about 0.5 to about 1.5 gallons per ton of potash.

6. The method of claim 4 wherein the mineral oil is a petroleum oilfraction.

7. The method of claim 4 wherein the mineral oil contains a small amountof pine oil.

8. The method of controlling dusting of finely-divided potash whichconsists essentially of intimately admixing finely-divided potash withfrom about 0.25 to about 5 gallons of mineral oil per ton of potash tosubstantially coat said potash with said mineral oil, said mineral oilbeing a petroleum fractionator still bottoms characterized by a pourpoint of from about 80 to 90 F., a viscosity of about 310 SSU at 100 F.,a 10% distillation temperature of about 510 F., a distillation end pointof about 875 F., a distillation residue of about 15 and an aromaticcontent of less than about 5 0%.

*9. The method of claim 8 wherein the mineral oil is employed in amountsof from about 0.5 to about 1.5 gallons per ton of potash.

10. The method of claim 8 wherein the mineral oil contains a smallamount of pine oil.

11. A nondusting potash material which consists essentially offinely-divided potash substantially coated with from about 0.25 to about5 gallons per ton of potash of a mineral oil characterized by a pourpoint of from about 30 F. to about 120 F., a viscosity of from about SSUto about 350 SSU at 100 F., a 10% distillation temperature above about500 F, a distillation end point below about 1000 F., a distillationresidue of not more than about 15% and an aromatic content of not morethan about 12. The finely-divided potash of claim 11 containing fromabout 0.5 to about 1.5 gallons of mineral oil per ton of potash.

13. A nondusting potash material which consists essentially offinely-divided potash substantially coated with from about 0.25 to about5 gallons per ton of potash of a mineral oil characterized by a pourpoint of from about 35 F. to about F., a viscosity of from about 100 SSUto about 310 SSU at 100 F., a 10% distillation temperature from about500 F. to about 700 F, a distillation end point below about 900 F, adistillation residue of not more than about 15% and an aromatic contentor" not more than about 50%.

14. The finely-divided potash of claim 13 containing from about 0.5 toabout 1.5 gallons of mineral oil per ton of potash.

References titted in the tile of this patent UNITED STATES PATENTS1,946,863 Koenders Feb. 13, 1934 2,164,089 Shumaker June 27, 19392,390,406 WegSt et a1. Dec. 4, 1945 2,413,491 Fajans Dec. 31, 19462,734,002 Schoeld et al. Feb. 7, 1956

1. THE METHOD OF CONTROLLING DUSTING OF FINELY-DIVIDED POTASH WHICHCONSISTS ESSENTIALLY OF INTIMATELY ADMIXING FINELY-DIVIDED POTASH WITHFROM ABOUT 0.25 TO ABOUT 5 GALLONS OF MINERAL OIL PER TON OF POTASH TOSUBSTANTIALLY COAT SAID POTASH WITH SAID MINERAL OIL, SAID MINERAL OILBEING CHARACTERIZED BY A POUR POINT OF FROM ABOUT 30* F. TO ABOUT120*F., A VISCOSITY OF FROM ABOUT 50 SSU TO ABOUT 350 SSU AT 100*F., A10% DISTILLATION END POINT BEPERATURE ABOVE ABOUT 500*F., A DISTILLATIONEND POINT BELOW ABOUT 1000*F., A DISTILLATION RESIDUE OF NOT MORE THANABOUT 15% AND AN AROMATIC CONTENT OF NOT MORE THAN ABOUT 60%.